//封装倒计时逻辑函数
//一个函数包括：返回值 参数 逻辑体
import { computed, onUnmounted, ref } from 'vue'
import dayjs from 'dayjs'
export const useCountDown = () => {
  //1、响应式数据
  let timer = null
  const time = ref(0)
  //格式化时间 xx分xx秒
  const formatTime = computed(() => dayjs.unix(time.value).format('mm分ss秒'))
  //2、开启倒计时函数
  const start = (currentTime) => {
    //开始倒计时逻辑
    //核心逻辑：每个一秒就减1
    time.value = currentTime
    timer = setInterval(() => {
      time.value--
    }, 1000)
  }
  //组件销毁时清除定时器
  onUnmounted(() => {
    timer && clearInterval(timer)
  })
  return {
    formatTime, start
  }
}